+ //Find the first Audio_item in the performance, so all staves start
+ //at the same tick.
+ Moment start_mom = 0;
+ for (vsize i = 0; i < audio_elements_.size (); i++)
+ if (Audio_item *item = dynamic_cast<Audio_item *>(audio_elements_[i]))
+ start_mom = min (start_mom, item->audio_column_->when ());
+